Intestinal Obstruction

Question 1

What are the common causes of Small Bowel Obstruction?

Answer 1

Extrinsic causes:

• Surgical adhesions
• Hernia
• Metastatic peritoneal cancer
• Volvulus

Intrinsic causes:
- Stricture in lumen (either Crohn’s or malignancy)

Intraluminal causes:

• Gallstone ileus
• Intussusception

Question 2

What are the common presenting features of intestinal obstruction?

Answer 2

Abdominal pain:
- Colicky

Distention:
- Prominent if large bowel, may not be so prominent if high obstruction as small amount of bowel proximal to obstruction.

Vomiting:
- Early sign if small bowel obstruction, may be late or absent in large bowel obstruction

Absolute Constipation:
- May be late sign of small obstruction, occurs early in large bowel obstruction.

Question 3

What are the examination findings in intestinal obstruction?

Answer 3

• Distention
• Dehydration
• Loud bowel sounds (tinkling in late disease)

If more advanced (peritoneal involvement):

• Rebound tenderness
• Percussion tenderness

Question 4

What investigations are carried out in intestinal obstruction?

Answer 4

Abdominal X-Ray:

• Small bowel obstruction = loops of dilated bowel, more central, striations go all the way across (circular mucosal folds)
• Large bowel = loops of dilated bowel, more laterally, haustrations of taenia coli do not extend across whole width.

CT with oral contrast:
- Localise site of obstruction and detect obstructing lesions.

Contrast enema (NOT oral barium, this is accumulate proximal to obstruction causing impaction)

Question 5

What is the managment of bowel obstruction?

Answer 5

Medical:
- Fluid resus
- NG decompression
(if obstruction partial/low-grade with history of abdominal surgery and no hernias, adhesions likely cause, 80% resolve with non-operative conservative management)

Surgery:

• If adhesions, mobilise and ensure blood supply
• If hernia, reduce and repair
• Any compromised bowel resected
• Neoplasm = resection

Question 6

What are the common causes of large bowel obstruction?

Answer 6

• Adenocarcinoma
• Scarring associated with diverticulitis
• Volvulus

Question 7

How is viability of the bowel determined?

Answer 7

Non-viable bowel:

• Loss of peristalsis
• Loss of normal ‘sheen’
• Colour (green/black = non-viable, purple may recover)
• Loss of arterial pulsation in supplying mesentry

Question 8

What is an important consideration with surgical treatment of obstruction?
How does this vary by site of obstruction?

Answer 8

If resection, anastamosis is a consideration:

• Small bowel: primary anastomosis can be made due to good blood supply
• Large bowel proximal to splenic flexure = primary anastomosis
• Distal to splenic flexure: Resection and bring ends out as colostomy, or closure of distal end (hartmann’s)
• Colonic primary anastomosis likely to leak.